Stepped Transmissions
Stepped transmissions are the most widely used type. They employ gear trains to provide a specific number of fixed gear ratios. Based on the type of gear train utilized, they are classified into two categories: fixed-axis transmissions (conventional transmissions) and rotating-axis transmissions (planetary gear transmissions). Transmissions in passenger cars and light-to-medium-duty trucks typically feature 3 to 5 forward gears and one reverse gear; however, compound transmissions used in heavy-duty trucks offer a greater number of gear ratios. The "number of gears" in a transmission typically refers specifically to the number of its forward gears.

Continuously Variable Transmissions (CVT)
Continuously Variable Transmission refers to a transmission system capable of providing any gear ratio within a specific range in a continuous, stepless manner. By enabling continuous variation, this system facilitates an optimal match between the powertrain and the engine's operating conditions. Common types of continuously variable transmissions include hydro-mechanical CVTs and metal-belt CVTs (VDT-CVT).

Integrated Transmissions
Integrated transmissions are a type of hydro-mechanical transmission consisting of a torque converter combined with a stepped gear transmission. In this system, the gear ratio can vary continuously (steplessly) within several discrete ranges situated between the maximum and minimum limits; this type of transmission is currently seeing widespread application.